The whalers said the whale was a cross between a fin and a blue whale, but experts have said the pictures show a juvenile blue whale.

“From the photos, it has all the characteristics of a blue whale,” Dr. Phillip Clapham, from the U.S. National Oceanic and Atmospheric Administration (NOAA) Alaska Fisheries Science Centre, told the BBC in a statement.

Ellen Coombs, a biologist at University College London told The Independent the whale had a lighter dorsal fin than a fin whale.

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She also said, “Now is the best time to see blues around Iceland, so I imagine that despite still being rare, their numbers around Iceland are at their highest during these months.”

Kristján Loftsson runs whaling company Hvalur hf, and stands by the assessment that the whale is a hybrid.

“To mistake a blue whale for a fin whale is impossible — this whale has all the characterizations of a fin whale in the ocean,” Loftsson told the BBC.

“There are a lot of blue whales off the Iceland coast — when we see the blows and sail to it, and we realize it is a blue and then we leave it and go and look for fin whales.”

“The killing of a possible blue whale or blue/fin whale hybrid, even if unintentional, demonstrates the difficulty for whalers at sea to identify which species they are actually pursuing,” Sigursteinn Masson of the International Fund for Animal Welfare wrote in a blog post.

“The result is that a protected species ultimately suffers the collateral damage resulting from an unnecessary and increasingly unpopular hunt.”

Bill Welch flew the drone that caught the footage of the whale for marine conservation organization Sea Shepherd.

“I couldn’t believe what I was seeing. I mean, nobody should see what I’ve seen,” he said.

“It goes against everything that I believe in. In fact, it’s gonna hurt the tourism industry in Iceland if they continue this.”

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Anti-whaling organization Hard to Port said they were working with marine conservationists to determine the species of the whale.

“Was No. 22 a “Blue”? Hard To Port’s observation and documentation work has revealed that the 22nd whale landed at Iceland’s whaling station was not a fin whale,” the organization wrote on Instagram.

“If our assumption proves to be true, we will make sure this will have some serious consequences for Kristján Loftsson and his company.”

Blue whales, the largest animal on the planet, can grow up to 200 tons. The World Wildlife Funds says its heart is the size of a Volkswagen, and lists its status as endangered.

It’s illegal to hunt blue whales in Iceland and in most places.

But it is legal to hunt fin whales in Iceland, even though their status is listed as endangered as well.

“Next to the blue whale, the fin whale is the second largest mammal in the world,” the WWF states on its website.